Oil-heating system



Jan. 21, 1930. F. E. LICHTENTHAELER 1,744,318

OIL HEATING SYSTEM Filed Oct. 11,` 1927 Patented Jan. 21, 193i) UNITED tSTATES PATENT orrlcr.

OIL-HEATING sYs'rnM Application filed October 11, 1927.

This invention relates to oil heating systems for use in the distillation of petroleum or the like, and more particularly to continuously operating systems employing tubes through which the oil to be heated is forced.

In systems of this kind, the velocity of oil flow through the tubes should be maintained at a high rate in order to secure the best efig ciency of heat transfer. In such systems as l0 heretofore designed, it has been the practice to employ comparatively few tubes in parallel and to cause the oil to trace a prolonged path through the furnace by connecting the tubes, or small groups of them, in series. The

frictional resistance to the 'liow of the oil in such a system, on account of the comparatively small total available cross section, is a serious consideration. In many cases, it has been found necessary to operate supply pumps at an excessive pressure of one hundred pounds or more and most of this pressure represents merely wasted work in opposing and overcoming the tube friction. With these consid erations in mind, an object of my invention is to provide an oil heating system in which the available tube area shall be large enough to permit rapid circulation of the oil at inodorate pressure. It is also important to avoid n local overheating and consequent cracking of "u the oil, especially when dealing with oils that must be heated to high temperatures for fracw tional distillation. The system which I have devised obviates these diiiiculties and insures uniform heating of the oil passing through it.

In one of its aspects, my invention, consists in a plurality of tubes disposed in parallel and traversing a heated furnace iue, with suitable connections for causing a rapid and easy circulation of the oil through the tubes at comparatively low pressure. Suitable means for controlling the circulating flow, for admitting cool oil to the system and for discharging heated oil to the fractionating tower are also provided and comprise additional features of my invention..

These and other features of the invention will be best understood and appreciated from the 'following description of a preferred embodiment thereof, selected for purposes of illustration and shown in the accompanying Serial No. 225,462.

drawing, in which the system is illustrated more or less diagrammatically.

In the drawing, l2 indicates the heated flue of a furnace having walls l() and in which the heated gases are drawn downwardly. The heating of the oil occurs in a series of tubes 14 disposed in parallel, traversing the heated Hue 3.2 and being connected at one end to an intake manifold 16 and at the other to a discharge manifold 18. The manifolds are tapered in opposite direction from their point of connection to the piping of the system. The heated oil passes upwardly from the discharge manifold 18 through a discharge pipe 22, leading to a reservoir 24 located above the tubes 14C and maintained nearly full of hot oil by the discharge pipe 22.

Oil is forced into the intake manifold 16 through the pipe 20, which takes the discharge of a hot oil pump 36, driven by a vari able speed motor 38. Oil is supplied to the hot oil pump through an inlet pipe 27 and to this is connected a vertical discharge pipe 26 leading from the bottom of the reservoir 24 and having a valve 30 for controlling the flow of oil from the reservoir.

The system as describedto this point is a completely closed system, in which the oil may be circulated and recirculated until its temperature israised to any desired degree, the rate of circulation being controlled by the valve 30 and the degree of temperature shown by thermometers placed in the inlet pipe 2O and the discharge pipe 22.

If it should be desired to discharge some of the heated oil from the system, the valve 30 may be closed, whereupon the level of the oil in the reservoir 24 will be raised to the height of a discharge pipe 29 which leads from it to the fractionating tower 34 at a point somewhat above the entrance of the pipe 22. Hot oil and hot oil vapor will thereupon be discharged from the reservoir to the fractionating tower, a valve 28 being provided in the pipe 29 for controlling flow at this particular point.

For supplying cool oil to the system, there is provided a supply pipe 42 leading to a centrifugal pump 410 and then through a valve 32 to the supply pipe 27. By this means, the

system may be filled with cool oil prior to setting it in operation or a controllable amount of cool oil may be continuously supplied during the operation of the system. 5 While I have shown but a single group of pipes in parallel, it will be understood that other similar groups of pipes may be connected in series if it should be found desirable to repass the oil across the heated fines repeatedly, but in every ease the group of pipes will afford a. relatively large cross sectional area for the rapid flow of the heated oil. It will be understood also that the telnerature of the Hue gases and the heat in the ue 12 is subject to control to avoid the danger of overheating the first tubes which meet the heat.

The system herein disclosed is so organized that the oil to be heated is caused to flow into the furnace tubes 14 by means of the circulating pump 36 which is of the required capacity and power to cause high velocity of flow through the tubes. The oil is heated in its rapid flow through the tubes in parallel g5 and then emerges from the furnace and re turns to the suction of the pump. The oil is thus repeatedly recirculated through the heated tubes at a high rate of ow but without undue frictional pressure because of the large cross sectional area provided by the tubes. When the oil has reached the required temperature, the discharge valve Q8 is opened and an amount of hot oil continuously withdrawn equal to the amount of cool oil entering through the supply pipe 42. When the system is established in operation, cool oil enters the pump, a constant volume of oil is recirculated through the tubes of the furnace at any desired velocity and hot oil of the desired temperature is discharged to the fractionating tower.

While I prefer generally to introduce a considerable fraction of the liquid entering the system into the fractionating tower either as vapor or as a mixture of vapor and liquid, it may develop that the liquid flowing down the pipe 26 from the reservoir Q4 is suiiciently stripped of its volatile constituents for the case in hand so that it is satisfactory for removal as a stripped residuum. This may be effected through the outlet 44 leading from the vertical pipe 26. It will be understood that it is the recirculation which makes possible a stripping out of volatile constituents in the residuum to a degree which would not otherwise be possible.

Having thus described my invention, what I claim is:

An oil heating system comprising a heated furnace flue, vertically disposed intake and discharge manifolds disposed in opposite sides of the flue and being tapered iu opposite directions, a plurality of short horizontal tubes connecting said manifolds and pro- 05 viding passage for a relatively large amount 

